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Date: Thu, 05 Feb 2015 12:07:06 -0800
From: Stephen Boyd <sboyd@...eaurora.org>
To: Sylwester Nawrocki <s.nawrocki@...sung.com>,
Tomeu Vizoso <tomeu.vizoso@...labora.com>
CC: linux-kernel@...r.kernel.org,
Mike Turquette <mturquette@...aro.org>,
Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
Paul Walmsley <paul@...an.com>,
Tony Lindgren <tony@...mide.com>,
Russell King <linux@....linux.org.uk>,
linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v13 3/6] clk: Make clk API return per-user struct clk
instances
On 02/05/15 11:44, Sylwester Nawrocki wrote:
> Hi Tomeu,
>
> On 23/01/15 12:03, Tomeu Vizoso wrote:
>> int __clk_get(struct clk *clk)
>> {
>> - if (clk) {
>> - if (!try_module_get(clk->owner))
>> + struct clk_core *core = !clk ? NULL : clk->core;
>> +
>> + if (core) {
>> + if (!try_module_get(core->owner))
>> return 0;
>>
>> - kref_get(&clk->ref);
>> + kref_get(&core->ref);
>> }
>> return 1;
>> }
>>
>> -void __clk_put(struct clk *clk)
>> +static void clk_core_put(struct clk_core *core)
>> {
>> struct module *owner;
>>
>> - if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
>> - return;
>> + owner = core->owner;
>>
>> clk_prepare_lock();
>> - owner = clk->owner;
>> - kref_put(&clk->ref, __clk_release);
>> + kref_put(&core->ref, __clk_release);
>> clk_prepare_unlock();
>>
>> module_put(owner);
>> }
>>
>> +void __clk_put(struct clk *clk)
>> +{
>> + if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
>> + return;
>> +
>> + clk_core_put(clk->core);
>> + kfree(clk);
> Why do we have kfree() here? clk_get() doesn't allocate the data structure
> being freed here. What happens if we do clk_get(), clk_put(), clk_get()
> on same clock?
>
> I suspect __clk_free_clk() should be called in __clk_release() callback
> instead, but then there is an issue of safely getting reference to
> struct clk from struct clk_core pointer.
>
> I tested linux-next on Odroid U3 and booting fails with oopses as below.
> There is no problems when the above kfree() is commented out.
>
>
Ah now I get it. You meant to say that of_clk_get_by_clkspec() doesn't
return an allocated clk pointer. Let's fix that.
----8<----
From: Stephen Boyd <sboyd@...eaurora.org>
Subject: [PATCH] clkdev: Always allocate a struct clk in OF functions
of_clk_get_by_clkspec() returns a struct clk pointer but it
doesn't create a new handle for the consumers. Instead it just
returns whatever the OF clk provider hands out. Let's create a
per-user handle here so that clk_put() can properly unlink it and
free it when the consumer is done.
Fixes: 035a61c314eb "clk: Make clk API return per-user struct clk instances"
Reported-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
---
drivers/clk/clkdev.c | 44 +++++++++++++++++++++++---------------------
1 file changed, 23 insertions(+), 21 deletions(-)
diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index 29a1ab7af4b8..00d747d09b2a 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -29,15 +29,8 @@ static DEFINE_MUTEX(clocks_mutex);
#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
-/**
- * of_clk_get_by_clkspec() - Lookup a clock form a clock provider
- * @clkspec: pointer to a clock specifier data structure
- *
- * This function looks up a struct clk from the registered list of clock
- * providers, an input is a clock specifier data structure as returned
- * from the of_parse_phandle_with_args() function call.
- */
-struct clk *of_clk_get_by_clkspec(struct of_phandle_args *clkspec)
+static struct clk *__of_clk_get_by_clkspec(struct of_phandle_args *clkspec,
+ const char *dev_id, const char *con_id)
{
struct clk *clk;
@@ -47,6 +40,8 @@ struct clk *of_clk_get_by_clkspec(struct of_phandle_args *clkspec)
of_clk_lock();
clk = __of_clk_get_from_provider(clkspec);
+ if (!IS_ERR(clk))
+ clk = __clk_create_clk(__clk_get_hw(clk), dev_id, con_id);
if (!IS_ERR(clk) && !__clk_get(clk))
clk = ERR_PTR(-ENOENT);
@@ -54,7 +49,21 @@ struct clk *of_clk_get_by_clkspec(struct of_phandle_args *clkspec)
return clk;
}
-static struct clk *__of_clk_get(struct device_node *np, int index)
+/**
+ * of_clk_get_by_clkspec() - Lookup a clock form a clock provider
+ * @clkspec: pointer to a clock specifier data structure
+ *
+ * This function looks up a struct clk from the registered list of clock
+ * providers, an input is a clock specifier data structure as returned
+ * from the of_parse_phandle_with_args() function call.
+ */
+struct clk *of_clk_get_by_clkspec(struct of_phandle_args *clkspec)
+{
+ return __of_clk_get_by_clkspec(clkspec, NULL, __func__);
+}
+
+static struct clk *__of_clk_get(struct device_node *np, int index,
+ const char *dev_id, const char *con_id)
{
struct of_phandle_args clkspec;
struct clk *clk;
@@ -68,7 +77,7 @@ static struct clk *__of_clk_get(struct device_node *np, int index)
if (rc)
return ERR_PTR(rc);
- clk = of_clk_get_by_clkspec(&clkspec);
+ clk = __of_clk_get_by_clkspec(&clkspec, dev_id, con_id);
of_node_put(clkspec.np);
return clk;
@@ -76,12 +85,7 @@ static struct clk *__of_clk_get(struct device_node *np, int index)
struct clk *of_clk_get(struct device_node *np, int index)
{
- struct clk *clk = __of_clk_get(np, index);
-
- if (!IS_ERR(clk))
- clk = __clk_create_clk(__clk_get_hw(clk), np->full_name, NULL);
-
- return clk;
+ return __of_clk_get(np, index, np->full_name, NULL);
}
EXPORT_SYMBOL(of_clk_get);
@@ -102,12 +106,10 @@ static struct clk *__of_clk_get_by_name(struct device_node *np,
*/
if (name)
index = of_property_match_string(np, "clock-names", name);
- clk = __of_clk_get(np, index);
+ clk = __of_clk_get(np, index, dev_id, name);
if (!IS_ERR(clk)) {
- clk = __clk_create_clk(__clk_get_hw(clk), dev_id, name);
break;
- }
- else if (name && index >= 0) {
+ } else if (name && index >= 0) {
if (PTR_ERR(clk) != -EPROBE_DEFER)
pr_err("ERROR: could not get clock %s:%s(%i)\n",
np->full_name, name ? name : "", index);
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
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